|
Definition:
|
Soil, rock or organics that had been subjected to temperatures below 0C for several consecutive years in the past. Often, micro-indicators of paleopermafrost are visible on geological profiles, such as ice wedge shapes, soil particle sorting or paleo-cryoturbation. Paleopermafrost is identified using micro-morphological indicators, such as vesicular or lamellar structures, structures of compacted silt deposits and transport, preferential orientation of certain grain sizes, structural plane banded, laminar micro-frost weathering, carbonation and hydrolysis of Fe. Signs of paleopermafrost are important indicators for the reproducing paleo-climatic conditions since it indicates possible variations in the 0C isotherm, and indirectly provides information on paleo-temperatures and when the mean annual soil temperatures increased above freezing. This phenomenon can be observed Patagonia and the Andes.
|